questions about buffer size and parameter size.

Would you please post your compilation log or whatever error you get? Are you talking about kernel compilation or host compilation here?

The size of your cl_mem buffer has nothing to do with kernel compilation, because the kernel compiler only sees the pointer to the buffer and does not know or care about the actual size of the buffer. The host compiler does not care about the size of the buffer either, you will just get an out of memory error from the OpenCL runtime during execution if your buffer is larger than the physically-available on-board memory. The only case your compilation will fail is when you try to create a very large "local" buffer on the FPGA.